The regenerative capacity of injured tissues in adult humans is often limited, particularly with advancing age or diseases such as diabetes. Literature suggests that electrical, electrothermal, and electromechanical stimulation can enhance repair of wounds by stimulating vascularization, cell migration and cell proliferation as well as other processes. This process is often referred to as electrotherapy or electromagnetic therapy. The process depends on the application of an electric current via electrodes or an electromagnetic field to an area of a tissue, usually a wound. The flow of electricity is dependent upon the natural conductive processes of the treated tissues. Nerve repair is also reported to be stimulated by this process. In general, there are many clinical situations which would benefit from the directed application of electrotherapy, particularly if more effectively applied and if repair was directed and localized rather than random. Synthetic polymers have been used to enhance current flow to stimulate neurite outgrowth in tissue culture.
While it is possible to incorporate a variety of growth factors into these materials, there are advantages in accelerating repair and regeneration by enhancing the body's natural repair processes. Pulsed electromagnetic field therapy has been investigated, particularly with respect to bone repair. In brief, an electromagnetic field is generated with a device over the tissue site of interest and maintained for various periods of time. Among the results reported are more rapid healing of fractures, particularly recalcitrant fractures, induction of vascularization in ischemic tissues, and enhanced nerve growth. Further silver ions generated by the field may have the ability to suppress bacterial growth.
Methods to deposit collagen molecules in defined structures including aligned, woven and transparent materials convertible into bandages, sutures and multilayered structures for diverse indications are described in U.S. patent application Ser. Nos. 11/951,324, 11/986,263, 12/106,214, and 12/539,563, all of which are incorporated by reference herein in their entirety. One advantage of these collagen materials is that they closely approximate the natural structures of tissues, are biocompatible and induce the guided growth of cells attaching to them. The collagen materials appear to be an excellent substrate for applying mesenchymal and other stem cells to precise tissue sites. While these advances have been made, there is need for continued advancement and development of materials, constructs, implants and methods that promote and/or enhance tissue repair and regeneration.